1. Field of the Invention
The present invention relates generally to specialized tools for performing vehicle maintenance, and more particularly to an improved modular tool for replacing a brake camshaft bushing seated within a bore in a suspension chassis of a truck or other vehicle.
2. Description of the Related Art
Attention is directed initially to FIG. 1 for an explanation of the relevant prior art. Heretofore, the task of inserting a camshaft bushing 6 housed within a bore 4 in a suspension chassis 2 has commonly been performed using a tool 10. Tool 10 is formed from a solid length of round steel bar stock and includes a handle portion 12, a proximal end 14, and a radial step 16 for transition to a radially reduced portion 18. The diameter of radially reduced portion 18 is sized for axially slidable fit within camshaft bushing 6, while the diameter of handle portion 12 is undersized relative to the diameter of chassis bore 4. In a typical replacement procedure according to the prior art, a mechanic pries the existing grease seals 8A, 8B out of chassis bore 4 using a screwdriver or similar tool, inserts reduced portion 18 of tool 10 into camshaft bushing 6 until an end of the camshaft bushing is engaged by radial step 16, and then drives the tool 10 by striking proximal end 14 with a hammer to push camshaft bushing 6 out the opposite end of the chassis bore. It is also possible for the mechanic to push the backside grease seal 8B out along with camshaft bushing 6 using tool 10. Insertion of a new camshaft bushing 6 into chassis bore 4 is performed by sliding the camshaft bushing onto radially reduced portion 18 of tool 10, driving tool 10 with camshaft bushing 6 axially into the bore by striking proximal end 14 with a hammer until the camshaft bushing is at a suitable depth allowing space in the bore for greases seals 8A, 8B, and then hammering the grease seals in place in the bore.
Certain drawbacks of this prior art methodology can be attributed to tool 10. First, it is necessary for a service station to absorb the expense of owning six or more tools 10 of different sizes to accommodate the common camshaft bushing sizes known in the industry. Second, tool 10 does not limit or control the depth to which camshaft bushing 6 is inserted into the bore, leaving this to the skill of the mechanic. Third, tool 10 does not install grease seals 8A, 8B, and the mechanic must perform the additional operation of hammering the grease seals into the bore. This operation can prove frustrating and imprecise, since the greases seals tend to flip or rotate back and forth in the bore with each off-center hammer blow. Fourth, the design of tool 10 is inherently massive since handle portion 12 is radially larger than reduced portion 18, thereby offering significant resistance to the transfer of driving force from a hammer to the camshaft bushing 6. Fifth, the unitary construction of tool 10 necessitates replacement of the entire tool even if only a portion of the tool is damaged.
Therefore, it is an object of the present invention to provide an improved tool for replacing a brake camshaft bushing in a suspension chassis that is capable of performing both removal and installation functions with respect to the camshaft bushing and associated grease seals.
It is another object of the present invention to provide an improved tool for replacing brake camshaft bushings of different sizes, thereby eliminating the need to purchase a set of differently sized tools.
It is another object of the present invention to provide an improved tool for replacing brake camshaft bushings that is less massive than tools of the prior art for better transfer of driving forces.
It is another object of the present invention to provide an improved tool for replacing brake camshaft bushings that includes removable parts that are less expensive to replace than an entire tool of the prior art in cases of wear or damage.
It is a further object of the present invention to provide an improved tool for replacing brake camshaft bushings that is modular in design for realizing the objects stated above.
In view of these and other objects, a modular tool formed in accordance with a preferred embodiment of the present invention includes a handle, a detent, a push ring, and a bushing carrier respectively connected in sequence by a threaded fastener extending through axially aligned through-holes in the bushing carrier, push ring, and detent for mating with a tapped hole in the handle. The detent is preferably a washer that is oversized relative to the chassis bore to limit insertion of the tool. The push ring is preferably a smaller washer having an outside diameter that allows the push ring to engage an annular end of the camshaft bushing without extending beyond the outside diameter of the camshaft bushing. The bushing carrier is a cylindrical component sized for slidably receiving the camshaft bushing thereon. Accordingly, a plurality of push rings and bushing carriers of different sizes can be provided along with the handle and the detent to accommodate different standard bushing sizes.
The tool is configured without the detent for driving an existing camshaft bushing and grease seals out of the chassis bore by striking an end of the handle with a hammer. The tool is configured with the detent for installing a new camshaft bushing and grease seals mounted on the bushing carrier, whereby the push ring sets the camshaft bushing and a distal grease seal at a proper depth in the bore and the detent applies evenly distributed pressure to a proximal grease seal to be flush with an end of the bore when the handle is struck with a hammer.